The present invention relates to rotary sprinklers, and particularly to the type of rotary sprinkler including a reaction member which oscillates an arm to impart the rotary motion to the sprinkler.
Rotary sprinklers of the foregoing type generally include a rotably mounted sprinkler head having a discharge nozzle discharging a water jet forwardly of the sprinkler head, an oscillating arm for periodically impacting the sprinkler head to impart a rotary motion thereto, a spring urging the oscillating arm in one direction, and a reaction member carried by the oscillating arm for moving the arm in the opposite direction by reaction forces. U.S. Pat. No. 3,022,012 discloses one such type of rotary sprinkler in which the reaction arm is of S-configuration so that the water is discharged from the outlet end of the reaction member in the same direction as that discharged from the discharge nozzle, to thereby minimize side splash. Similar constructions are described in U.S. Pat. Nos. 4,164,324 and 4,182,494, and are used in commercially-available sprinklers. In all such known constructions, the reaction member, including both its inlet and its outlet end, the axis of the reaction member is substantially planar.
I have found that such constructions produce a limited force tending to rotate the sprinkler head, and therefore if the pressure of the supply line supplying the water to the sprinkler head drops below a predetermined value, there may be insufficient force to rotate the sprinkler head especially when low discharge rates are desired. This is particularly true if the sprinkler is of the sector-type requiring sufficient energy from the water supply line not only to rotate the sprinkler head, but also to operate the reversing mechanism for reversing its direction of rotation.